Method and apparatus for a file sharing synchronization system

ABSTRACT

A computer-implemented method is provided for managing and sharing picture files. In one embodiment of the present invention, the method comprises providing a server platform and providing a datastore on the server platform for maintaining full resolution copies of the files shared between a plurality of sharing clients. A synchronization engine is provided on the server platform and is configured to send real-time updates to a plurality of sharing clients when at least one of the sharing clients updates or changes one of said files. A web interface may also be provided that allows a user to access files in the datastore through the use of a web browser.

The present application claims the benefit of and priority to U.S.Provisional Patent Application No. 60/626,121 entitled “Method andApparatus for a File Sharing and Synchronization System” and filed onNov. 8, 2004, and is hereby, incorporated by reference.

TECHNICAL FIELD

The field of the invention generally relates to data management, andmore specifically, to methods of synchronizing data used in personalinformation managers or other programs, especially when the file or datais used or shared among multiple computing devices.

BACKGROUND

File sharing and data management, in general, is a problem today. Withall of the various types of files on different devices such as personalcomputers, personal digital assistants, or cellular phones, themanagement of data in an efficient manner from device-to-device is achallenge for users.

In the context of data files in general, files worked on at one locationby a user may not be accessible from a device at another location. Forexample, a user working at home may have files left there on a homecomputer that are not accessible from a computer at work. Data on onedevice may be lost because the user failed to regularly back-up the datafiles on the device. In other situations, short of forwarding each fileor email to another account, switching accounts at an interne serviceproviders may cause a user to lose their emails and other personal filesresident on that ISPs server. All of these problems with dataportability, management, and access create inefficiencies for a user.

Some known systems have tried to address these issues. In the photosharing context, websites such as Ofoto have allowed users to load filesto the Ofoto website to share among multiple devices and multiple users.This does allow some access to images when the user is not at his/herhome computer and to share photos with users at remote locations. Thesharing of files, however, among multiple users is typically limited tolow-resolution versions of the original images, and this sharing oflower quality files may cause a user difficulty in viewing the image.Additionally, there is no data persistence as the files on the servermay be deleted after a certain period of inactivity. In systems whereusers use peer-to-peer sharing or email picture files to each other,images may be lost or hard to track down because the original email waslost or poorly organized among the users files. Additionally, dynamicupdating of shared files is not present. The data or file is copied onetime and is then static on the sharee's system.

SUMMARY

The present invention provides solutions for at least some of thedrawbacks discussed above. Specifically, some embodiments of the presentinvention provide a repository for a database of files shared in-sync,in real-time across multiple computers or computing devices. Embodimentsof the present invention may provide an improved desktop or clientapplication which offers easy sharing of files, automaticsynchronization, file access from anywhere, and transparent backup. Thepresent invention desires to be user centric (instead of computer ordesktop centric) in the sense that the user can access the user's dataregardless of which physical computer or device the user is using. Atleast some of these and other objectives described herein will be met byembodiments of the present invention.

In one embodiment of the present invention, an improved data managementsystem is provided. The system may comprise a server platform thatenables synchronization, back-up, web access, and sharing ofapplications and data. This allows for a user's data to be accessiblefrom any pc or web browser. Changes to files, email, and/or calendarentries may be synchronized automatically across a user's computers. Theshared files will be updated including but not limited to new metadata,improvements to the files, or the like. The system may be configured fortransparent backup to a central server. Such systems give the user anability to reproduce applications with the user's settings and data onany computer with “one click”.

In another embodiment of the present invention, a native suite of clientapplications may be provided that allows for management and access ofall the user's data locally on the user's hard drive. The clientapplications may be downloaded to reside on a user's computer andprovide access to a server platform that functions to synchronize filesacross multiple computing devices and allows for backup of the user'sfiles. The client applications may allow for management of personalemail, photo files, video files, personal calendar entries or the like.A rich user interface is provided to make file access and managementfast and easy. The client applications take the thinking out of datamanagement and back-up by making it automatic and transparent.

In another embodiment of the present invention, a synchronization engineis provided that allows users to synchronize metadata on files on thesystem. By way of example and not limitation, this is particularlyuseful in the sharing of electronic photos where collaborative taggingof files by different users may be enabled by the invention to moreaccurately organize and search for picture files. The updating andsynchronizing of metadata allows all users to benefit from more detailedmetadata that may be provided by one user, which is then cascaded orpushed to picture files resident on other computers of other users thatshare the file.

In one aspect, the present invention allows for the persistence of data.The user can change computers, emails accounts, but the emails, photos,or other user files may persist and can be downloaded to the user'ssystem at different computer terminals or portable devices. Theseapplications may be accessed through a web application if the user is ona public terminal or if the user is at a computer they do not own. Theclient may be also be downloaded to the computer. The present inventionprovides real-time, synchronized storage of a users files at a centralserver. This creates a backup for the user and no longer ties the userto any one particular physical device, so long as the user has access tothe server.

A further understanding of the nature and advantages of the inventionwill become apparent by reference to the remaining portions of thespecification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included as part of the presentspecification, illustrate the presently preferred embodiment of thepresent invention and together with the general description given aboveand the detailed description of the preferred embodiment given belowserve to explain and teach the principles of the present invention.

FIG. 1 illustrates a block diagram of an exemplary client serverarchitecture, according to one embodiment of the present invention;

FIG. 2 illustrates a block diagram of an exemplary process forsynchronizing a data object amongst the clients, according to oneembodiment of the present invention;

FIG. 3 illustrates a block diagram of an exemplary architecture of aserver platform, according to one embodiment of the present invention;

FIG. 4 illustrates a block diagram of an exemplary photo sharingapplication, according to one embodiment of the present invention;

FIG. 5 illustrates a block diagram of an exemplary synchronizationarchitecture, according to one embodiment of the present invention; and

FIG. 6 illustrates a block diagram of an exemplary method is providedfor aggregating messages from multiple email accounts into a singlevirtual account which is synchronized across multiple computers anddevices, according to one embodiment of the present invention.

DETAILED DESCRIPTION

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed. It may be notedthat, as used in the specification and the appended claims, the singularforms “a”, “an” and “the” include plural referents unless the contextclearly dictates otherwise. Thus, for example, reference to “aprocessor” may include may include multiple processors, and the like.References cited herein are hereby incorporated by reference in theirentirety, except to the extent that they conflict with teachingsexplicitly set forth in this specification.

A “server” in a hardware configuration may be a computer such as apersonal computer (PC) or other intelligent device. A server typicallyperforms the bulk of the centralized or generalized tasks in the networkand often has more memory, processing speed, and storage than the otherdevice on the client-server network. Alternatively, the server mayperform specialized tasks such as distributing electronic mail, datastorage or printing. In the software arrangement, a “server” typicallyis a program that provides data, stores data, or provides some serviceto other programs to lo which the server is connected. A server may be aprogram with higher priority, greater memory, or greater capabilitiescompared to the other programs connected through the network. A serveralso may be a program that includes specialized capabilities or hashigher priority with respect to certain tasks or functions.

A “client” in the software arrangement is generally a program used by auser. A client program typically makes use of data, processing, storage,or other resources of another program. A client may be used tocommunicate with a source or destination through a higher priority, morepowerful, more capable or different program. The client may run on acomputer such as a personal computer (PC), intelligent device, personaldigital assistant (PDA) or workstation used by a user. In use, theclient may carryout tasks in the process of which the client may requestinformation or otherwise may use the resources of another object such asthe server or another client to accomplish such tasks.

Synchronization

Referring now to FIGS. 1 and 2, one embodiment of a system for sharingfiles among multiple computing devices will now be described. One of thecomponents of the present invention is that if a user has multiplecomputers, the data is kept in-sync and in real-time across all of theusers computers connected to a network. If the user makes a change onone computer to the database or a file, the change is synchronized tothe server and synchronized in real-time to the user's other computers.This means that changes made on one computer are kept up-to-date on theserver. The user can sit down at any of the user's other computers (orat a set of computers defined by the user) and pick-up where the userleft off. The user can also log onto to a website and using a webapplication, pick-up where the user left off. This allows the user'sfiles to be accessed from any number of different workspaces.Additionally, it should be understood that clients that run on mobiledevices may be used to access the user's files.

FIG. 1 shows how computers or devices running clients 10, 12, 14, 16,and 18 may be coupled to each other via servers. FIG. 1 is a logicaldiagram of various clients communicating through a server platform.Client 10 and client 12 are able to hook into the wide area network 20by means of logically connecting to a server 22. The wide area network20 could be the Internet or an intranet or any other such wide areanetwork or even a local area network. In like manner, client 14 hasaccess to the wide area network 20 through server 24 and client 16 andclient 18 have access through server 26. Although multiple servers areshown for this example, it should be understood that some embodimentsmay use only one server for the server platform to connect all sharingclients together.

The respective servers 22, 24, and 26 can communicate with one anotherdirectly or indirectly. The actual clients may not have the capabilityto communicate with any other entity besides the respective server towhich they arc connected but through the wide area network and theability of the servers to communicate.

The net effect of such an arrangement allows any client to communicatewith any other client through the transport connection between servers.This allows each client, regardless of the server to which it isconnected, the ability to send messages to each other client over thewide area network 20. In this manner, clients may be given the abilityto control replication as will be shown hereafter without regard to thetype of server to which they may be connected or the client's ability todirectly communicate with another client. By way of example and notlimitation, the servers 22, 24, and 26 may form a server platform and atleast one of the servers may run a synchronization engine fordistributing updates among different clients.

FIG. 2 is a schematic depicting the basic paradigm for synchronizing adata object amongst the clients. Referring to FIG. 2, changes or updates30 from a sharing client 34 will be sent to the synchronization engine32 which will forward or update a copy of a data object on each of theclients listed as part of the plurality of sharing clients 34 in orderto synchronize that data object with other sharing clients. Each clientpreferably has the ability to communicate with a server and have theappropriate software running thereon. The sharing client 34 may operateto synchronize a local database on the local computer with a remotedatabase, such as a server database on a datastore 40 in FIG. 3 that maybe maintained on one server or a server farm. In this example, theserver or server farm may be coupled to the network, and receive andtransmit communications via a firewall, provided by a server fain,provider, that implements well-know security features.

There are a variety of ways to notify the sharing clients 34 that achange has been made. In one embodiment of the present invention, ifchanges are made by one of the sharing clients 34 to a particular dataobject, an update message 30 is sent from the particular sharing clientto the synchronization engine 32. The synchronization engine, in turn,will make the particular adjustment to the original or copy of the dataobject on the server and distribute the data object out to each of thesharing clients 34. The update message 30 may include instructions, suchas a delete command to remove a particular data object or a modifycommand for modifying a particular data object. One way of representinga modification to an existing data object or the creation of a new dataobject is to include the actual data object in its modified form. Thusin some embodiments, updates are represented by sending a new copy ofthe entire object.

This two way synchronization may occur in real-time which, for exampleand not limitation, may occur with the files being updated whenever anautosave occurs to the data or file being edited. The autosaved versionmay be updated to the server having the synchronization engine and thenpushed out or cascaded to the sharing clients. Some sharing clients maybe configured to accept updates to files that are not currently beingedited on at the local client, to prevent any conflicts. In someembodiments, the user may be prompted that there has been an update on afile they are editing locally and may accept or reject the changes. Forchanges to metadata, some embodiments of the present invention may allowsimultaneous edits and merge them without notifying the user. If twousers are editing separate fields, both changes will persist. If bothusers modify the same field, one of the changes will be silentlydiscarded. For files, the user will be prompted to choose which versionto keep.

Referring now to FIG. 3, a schematic showing the architecture of aserver platform according to the present invention will now bedescribed. In this embodiment, the server platform may be at least oneserver 22 which has a synchronization engine 32 which communicates withsharing clients 34 running on devices which may be but are not limitedto desktop computers and laptop computers. This allows updates receivedby the server to be updated to the sharing clients 34. The sharingclients 34 may also communicate with each other as indicated by arrow36.

As seen in FIG. 3, the server 22 may include a datastore 40 that holdscomplete copies of the user files being shared. In a picture sharingenvironment, full resolution and complete copies of those files are alsoresident on the local computers of each sharing client 34. In otherwords, complete copies of files exist at the server level and at thelocal level for each of the computers or devices sharing the files. Adatabase engine 42 and file management engine 44 may also be used toorganize and access the files in the datastore 40.

FIG. 3 also shows that instead of using a sharing client 34, a webbrowser 50 may also be used to access the user files resident in thedatastore 40 of the server 22. Although a web browser such as MicrosoftInternet Explorer is shown in FIG. 3, it should be understood that avariety of other browsers such as Netscape, WAP browsers, or the likemay also be used. In one embodiment of the present invention, the server22 may include a web front end 52 that allows a user to access filessuch as shared photo files, email, data files, and/or calendar files.The web front end 52 may be a website or web application that allows theuser to access the datastore 40 for picture files, calendars, and/ordata files. In this embodiment, mail services and photo services mayalso be available through the web front end 52 through mail gateways onthe server (SMTP and POP/IMAP for sending and receiving email) and photogateways (printing gateways or MMS gateways for handling media files).Again, files in datastore 40 are again pushed out to other sharingclients 34 so that the most recent versions are available to the usersof the shared files.

Although files may be accessed through the web interface and are notlimited to the following, the primary method of accessing information isthrough a native client on the user's local hard drive or computingdevice. The files being accessed are accessed from the user's local harddrive. This also allows the user to access files while offline. Whenconnections are continuously available, the files are continuouslysynchronized. When a continuous connection is not available, then thenext time the user s connected, the changes will be synchronized.

In one embodiment, the sharing client 34 may have two modes of operationnamely (1) an off-line mode wherein the client machine is not connectedto the network and (2) an on-line mode wherein the client machine isconnected to the network. In the off-line mode, the sharing client 34performs only local operations. When operating in the on-line mode, theclient 34 will be configured to receive real-time updates with thesynchronization engine 32 to perform global synchronization operations.

When communications are first established between the server 22 and thedesktop computer, there are potentially a number of modified,unsynchronized objects on the two computers. Again there may be varietyof ways to determine which files need updating. Synchronization may bebased on the time of the last update or may be based on some othercriteria set by the user. For example and not limitation, the system mayutilize an appropriate sequence number scheme employed by the localdatabase on a sharing client 34. Specifically, a sequence number may becommunicated of the last activity with respect to the local database ofwhich the server database was aware. The synchronization engine 32 willthen communicate records for all activity occurrences that have sequencenumbers greater than the sequence number communicated. Other embodimentsmay have the synchronization engine maintain a log of changes. The logis provided to sharing client 34 when communications are established.The log indicates object identifiers for the objects that have beenmodified, added, or deleted in the server's datastore.

In some cases, an object will have changed in both the server and thelocal device. If so, the user is prompted to resolve the conflict bydeciding which modification should be retained. In one embodiment of theinvention, the server instance of the object is received by sharingclient 34 from a synchronization engine and used to create a new objectin desktop object store. The sharing client 34 may prompt a user todecide which of the two objects (server or client) should be retained.If the server version of the object is selected, it replaces the desktopversion. If the desktop version is selected, it is sent to the serversynchronization engine to overwrite the existing version of the objectin server object store.

FIG. 4 describes the application of the present embodiment of the systemto a photo sharing application. In this application, the application ofthe sharing client 34 allows PC-to-PC sharing of high-resolutionpictures. The full resolution copies of the pictures are resident on thecomputers running the sharing client 34 and also on the datastore 40 onthe server 22 of the server platform. The sharing client 34 may includebuddy lists and album group management to organize the files beingshared. In addition to picture files, other files such as but notlimited to videos and slideshows may also be shared.

When a user with a sharing client 34 makes changes to albums or files ona local computer, the changes are synchronized automatically across alldevices. The saved changes are sent from one sharing client 34 to thesynchronization engine 32 on the server 122. The synchronization engine32 will have the datastore 40 updated with the latest file and alsotransmit this latest version to other sharing clients 34 that aredesignated as sharing with the sharing client 34 that originated thechanges. Changes are synchronized even when annotation or metadata isupdated for a file. This allows for collaborative annotation of picturesor other files.

The present invention allows fast, easy access to high-resolution imageson the computer of each user sharing the files. Access is also availablethrough a website that mirrors the view from the user desktop.Furthermore, since full resolution copies of files are resident in thedatastore 40 of the server 22, server backup of shared pictures andapplication settings occur automatically. This allows for easyrestoration of application settings, preferences and data on any PC.

Two-Level Sharing:

Referring now to FIG. 5, in one aspect of synchronization, someembodiments of the present invention control the release of updates tocomputers outside of a defined subset 60 of computers. The presentinvention may provide a multi-phase commit process for shared files anddata objects where changes are visible only to a single user or group ofusers until they are published to a wider audience 62. By way of exampleand not limitation, updates the user makes to a file may be reflected onthe user's own computers, but not on any of the other computers (outsidethe subset) where the user has shared the file until the user publishesthe changes. It is a two-step file save process. The draft change mayalso be released to a subset of users who are sharing the document.

For example, an application may automatically save changes to a documentas a user edits it. These changes will be saved to the datastore andsynchronized to other computers belonging to the user who made thechanges. They will not be visible to other users until the owner choosesto publish them. This could be a multi-phase process where the changesare first published to a group which is a subset of all users who haveaccess to the data object before being published to a wider audience.This is analogous to a two phase commit in a transactional database witha few important distinctions. In a traditional database, the changedrecord is locked (inaccessible to other users) until the transaction iscommitted and uncommitted changes are only visible within a singlesession. In this model, the original object is not locked, and thechanges are stored in the database and are accessible to other sessions.

In one embodiment of the present invention, when a user first accesses arepository in the datastore, a separate logical branch is created. Thisbranch is accessible to the user from any computer. In the beginning,this branch is empty, and all accesses are passed through to theoriginal repository. As the user edits objects in the repository, therevisions are stored in the branch, and accesses to modified objectswill incorporate these revisions. When the user publishes his changes,the modified records in the branch will be integrated with the mainrepository, where they will be available to other users. It is possibleto create multiple levels of branches, some of which may be shared withother users, allowing the sharing of draft changes with a group of usersbefore they are committed. The user does not need to understand theconcept of a branch, only the concept of publishing changes.

For instance, in the photo sharing case, the user can modify a picturewith red eye reduction, after the user has already shared the originalfile with a plurality of people. Immediately, those changes will besynchronized across all of the user's multiple computers or device, butnot with the previous shares. Once the user is completely done editingthe picture, the server can publish the changes to all his/her shares.It should be understood of course that additional layers of sharing maybe implemented to more precisely control the level of access to anyparticular files. Some embodiments may have multiple layers of sharing.

File Restoration

Embodiments of the present invention may also provide a method forinstalling applications in which all of a user's settings and data areautomatically restored. An application utilizing the platform of thepresent invention will automatically synchronize all of its settings anddata to at least one server. When a user installs an application that hehas previously used on another system, all settings and data areautomatically restored to their most recent state as part of the installprocess. In the photo sharing instance, what this means is if a usersuffers a hard drive crash or other catastrophic loss of data, the usercan automatically reinstall the application and all the data, includingbuddy lists, album structures, preferences, etc., without having tomanually recreate it. If the system was configured to share these files,then the system will have a copy of the files on datastore 40.

Thus data is restored as it was, the last time the user used it. All ofthe preferences, applications, and data are the same as the last timethe user used it. A user would start the installer and would not need toreconfigure the computer to have the preferences and settings from thelast use.

Collaborative Metatagging

The present invention also allows for improved metatagging. Tagging ispainful and sometimes too much of a burden for a single user. Anyupdates or tagging will then be synchronized. The sharing experiencebecomes much richer when the files can be more accurately sorted throughmetadata. The collaborative tagging improves organizing of pictures. Forexample and not limitation, all the pictures that a user likes can besorted and will then be on the user local drive.

The present invention provides a method for allowing photo metadata tobe collaboratively created and edited. When a user shares a photo albumwith others, the user may choose to grant the recipients permission toupdate metadata relating to the photos in the album (e.g., location andpeople or objects in the pictures). In the present embodiment, thesechanges will be propagated to all recipients of the album, allowing themto search on the metadata. So, if one user is not organized enough toenter captions or people for the metadata for that file, if the usershares the album with a plurality of other people, changes entered byany of those people will be propagated to everyone sharing the files,thus enhancing everyone's viewing experience.

Email Aggregation and Synchronization

Referring now to FIG. 6, in another aspect of the present invention, amethod is provided for aggregating messages from multiple email accountsinto a single virtual account which is synchronized across multiplecomputers and devices. This will provide a non-browser method to accesspersonal email. In one embodiment of the invention, the server 22 checksall of a user's personal email accounts 80 and imports the messages intothe datastore 40. The messages are synchronized to all of the user'scomputers and devices, as are any further changes to the mailstore (e.g.deletions, flags, filing to a folder). The present invention givescustomers a virtual Microsoft Exchange experience for their personalemail. The layer of abstraction provided by the present invention willgive customers freedom from worrying about checking multiple differentemail accounts through a browser, and instead have access to one inbox,with one set of contacts, etc., that is replicated across all of theuser's computers and a server to allow the user to access from anywhere.So, if the user deletes an email message on one computer, or adds acontact to the client in one computer, the change is immediatelypropagated to all the other computers.

For the present invention, the email integration is based on: 1)aggregation of multiple personal email accounts (all from a centralplace and all on a central account) and 2) centralization on the serverto allow a user to access from multiple computers with the same inboxand contact list. If an email is moved on one server, it moves it in allinboxes. This occurs for personal email aggregated from POP, IMAPaccounts, etc). Files are synchronized by the server 22 to all otherclients which may access the integrated email. Thus, the presentembodiments build a synchronization engine and layer the email clientapplication on top of the synchronization engine. The datastoreintegrates with the synchronization engine to send updated files to thesharing clients.

Thus, the server 22 in this embodiment also handles aggregation ofemails from multiple accounts. The client runs on the local computer andaccesses the server with the datastore. The synchronization andaggregation occurs at the server. As mentioned, this system is for thepersonal email accounts. Multiple personal email accounts are checkedthrough multiple browsers or multiple sessions. In the user's localclient, the emails are aggregated. This creates some email portability.All the emails are on the local server and not just on the server of theemail service. The present invention provides real-time synchronizationamong multiple devices and provides aggregation of multiple personalemail accounts. The synchronization keeps the connection open at alltimes so that update changes will be reflected on the new computers.

In one embodiment of the invention, the mailstore will receive emailfrom the personal email accounts for integration and storage on adatastore 40 on server 22. Files on those personal email accounts maythen be deleted to reflect changes made in the mailstore. For exampleand not limitation, spam email that a user deletes from the files on themailstore will also be deleted from the individual personal accounts sothat they are not present if the user accesses the personal accountsdirectly. Most of these personal accounts are web-based, browser-basedaccounts. Updates that the user makes to mailstore on the server 22 willbe reflected back to those email services. Changes may be reflected backto the originating service via POP, IMAP, or another protocol such asbut not limited to Web-DAV.

While the invention has been described and illustrated with reference tocertain particular embodiments thereof, those skilled in the art willappreciate that various adaptations, changes, modifications,substitutions, deletions, or additions of procedures and protocols maybe made without departing from the spirit and scope of the invention.For example, with any of the above embodiments, the synchronizationengine may synchronize with a personal information module (PIM) (such asbut not limited to Microsoft Outlook or the Palm Desktop) or with aPersonal Digital Assistant (PDA) (such as but not limited to a Palmdevice or any Windows CE device). In a further alternative, the presentinvention may also be used to update a user's personal calendar. Thismay be a calendar that is separate from the one the user may have atwork. Additionally, the integrated email, calendar, and otherapplications may form a suite of applications where there is oneinterface accessed by the user that synchronizes multiple sources(emails, photos, and calendars). This will be a way to synchronize allpersonal data.

The publications discussed or cited herein arc provided solely for theirdisclosure prior to the filing date of the present application. Nothingherein is to be construed as an admission that the present invention isnot entitled to antedate such publication by virtue of prior invention.Further, the dates of publication provided may be different from theactual publication dates which may need to be independently confirmed.All publications mentioned herein are incorporated herein by referenceto disclose and describe the structures and/or methods in connectionwith which the publications are cited.

Expected variations or differences in the results are contemplated inaccordance with the objects and practices of the present invention. Itis intended, therefore, that the invention be defined by the scope ofthe claims which follow and that such claims be interpreted as broadlyas is reasonable.

1-20. (canceled)
 21. A method for updating metadata on a synchronizationserver, the method comprising: establishing, at the synchronizationserver, a connection with a client device; and upon establishing theconnection, receiving, from the client device, at the synchronizationserver, a notification of an update to metadata associated with a dataobject, the update to the metadata occurring prior to the establishingof the connection with the client device and while disconnected from theclient device; and receiving, at the synchronization server, a copy ofthe updated metadata from the client device.
 22. The method of claim 21,further comprising maintaining a continuous connection with the clientdevice.
 23. The method of claim 22, further comprising receiving,through the continuous connection, update notifications in real time.24. The method of claim 21, further comprising determining whether anupdate to the metadata has occurred.
 25. The method of claim 24, whereinthe determination is based on a time of last update.
 26. The method ofclaim 24, wherein the determination is based on a sequence numberscheme.
 27. The method of claim 21, further comprising: disconnectingfrom the client device; re-establishing a connection to the clientdevice; and upon re-establishing the connection, receiving notificationof another update to the metadata at the client device that occurredduring the disconnection.
 28. A non-transitory computer-readable mediumin a synchronization server for updating metadata, comprising: code forestablishing a connection with a client device; and code for receiving,upon establishing the connection, a notification of an update tometadata associated with a data object, the update to the metadataoccurring prior to the establishing of the connection with the clientdevice and while disconnected from the client device; and code forreceiving a copy of the updated metadata from the client device.
 29. Thecomputer-readable medium of claim 28, further comprising code formaintaining a continuous connection with the client device.
 30. Thecomputer-readable medium of claim 29, further comprising code forreceiving, through the continuous connection, update notifications inreal time.
 31. The computer-readable medium of claim 28, furthercomprising code for determining whether an update to the metadata hasoccurred.
 32. The computer-readable medium of claim 31, wherein thedetermination is based on a time of last update.
 33. Thecomputer-readable medium of claim 31, wherein the determination is basedon a sequence number scheme.
 34. The computer-readable medium of claim28, further comprising: code for disconnecting from the client device;code for re-establishing a connection to the client device; and code forreceiving notification of another update to the metadata at the clientdevice that occurred during the disconnection upon re-establishing theconnection.
 35. A synchronization server configured to: establish aconnection with a client device; and receive, upon establishing theconnection, a notification of an update to metadata associated with adata object, the update to the metadata occurring prior to theestablishing of the connection with the client device and whiledisconnected from the client device; and receive a copy of the updatedmetadata from the client device.
 36. The server of claim 35, furtherconfigured to maintain a continuous connection with the client device.37. The server of claim 36, further configured to receive, through thecontinuous connection, update notifications in real time.
 38. The serverof claim 35, further configured to determine whether an update to themetadata has occurred.
 39. The server of claim 38, wherein thedetermination is based on a time of last update.
 40. The server of claim38, wherein the determination is based on a sequence number scheme.